So, there are a few models of 1930ish Guildite tanks that show up on eBay somewhat routinely. Mostly rectangular models with flared and stepped sides, round movements. But if you believe what's in the Master Book, there were a whole slew of Guildite tanks made around that time, some oddball round models, tonneaus, and my favorite, the long narrow models with ladies movements and no sub-seconds. Yet, they never seem to turn up. I would guess nobody else is finding these either, so I'm not expecting much of a response. Just putting it out there that it's something I'm always looking for.

EDIT: I mean "tank" in the generic sense of a rectangular or barrel shaped watch, not specifically Gruen Tank line.